Rheinwald J G, Chakrabarty A M, Gunsalus I C
Proc Natl Acad Sci U S A. 1973 Mar;70(3):885-9. doi: 10.1073/pnas.70.3.885.
Earlier papers demonstrated an extensive genetic exchange among fluorescent Pseudomonads; this one documents for genes specifying enzymes of peripheral dissimilation an extrachromosomal array, segregation, and frequent interstrain transfer. An hypothesis is presented of a general mechanism for the formation and maintenance of metabolic diversity. The example used, the path of oxidative cleavage of the carbocyclic rings of the bicyclic monoterpene D- and L-camphor, terminates in acetate release and isobutyrate chain debranching. By transduction, two gene linkage groups are shown for the reactions before and after isobutyrate. The group for reactions before isobutyrate is plasmid borne, contransferable by conjugation, mitomycin curable, and shows a higher segregation rate from cells that are multiplasmid rather than carrying a single plasmid. The genes that code for isobutyrate and essential anaplerotic and amphibolic metabolism are chromosomal. By conjugation plasmid-borne genes are transferred at a higher frequency than are chromosomal, and are transferred in homologous crosses more frequently than between heterologous species. Most isobutyrate-positive fluorescent pseudomonad strains will accept and express the camphor plasmid.
早期的论文证明荧光假单胞菌之间存在广泛的基因交换；本文记录了指定外周异化酶的基因的一种染色体外排列、分离和频繁的菌株间转移。本文提出了一种形成和维持代谢多样性的一般机制的假说。所使用的例子，即双环单萜D-和L-樟脑的碳环氧化裂解途径，最终以乙酸盐释放和异丁酸盐链去分支结束。通过转导，显示了异丁酸盐前后反应的两个基因连锁群。异丁酸盐之前反应的基因群由质粒携带，可通过接合共转移，可被丝裂霉素治愈，并且从携带多个质粒而非单个质粒的细胞中显示出更高的分离率。编码异丁酸盐以及必需的回补和兼性代谢的基因位于染色体上。通过接合，质粒携带的基因比染色体基因转移频率更高，并且在同源杂交中比在异源物种之间转移更频繁。大多数异丁酸盐阳性荧光假单胞菌菌株将接受并表达樟脑质粒。
